Railroad hopper cars that carry bulk particulate materials or commodity, such as grain, food products, plastic pellets, powder, or other materials, have long been in use. Hopper cars generally have one or more compartments for storing and transporting these materials. Each compartment has at least one hatch in the roof of the car at the top of the compartment for loading materials into the compartment and at least one outlet at the bottom of the compartment for unloading of the materials. A hatch cover is provided for each hatch to close the compartment after loading and thereby prevent foreign matter and moisture from entering the compartment and contaminating the stored materials during transit.
Heretofore, it has been known to use a gasket to seal the connection between the hatch cover and the hatch. Generally, the gasket is adhesively attached to the hatch cover. Use of an adhesive, however, prohibits or hinders the removal of the gasket when the gasket becomes dirty or worn.
It has also been known to provide a hatch cover with a removable gasket as in U.S. Pat. No. 2,745,362 and U.S. Pat. No. 5,622,117. Both patents disclose a non-adhesive retention means for supporting the gasket on the cover. The '362 patent shows annular ribs extending from opposed flanges and underlying the edges of the gasket, while the '117 patent uses clips that extend from the flanges and hold the gasket in place. One problem with the use of ribs or clips as shown in the '362 and '117 patents is that contaminants from the outside air and contents within the cars can accumulate between the clips and the gasket, thereby deteriorating the sealant quality of the gasket. Furthermore, cleaning of the hatch-engaging face of the gasket requires removal of the gasket from the cover for cleaning under the ribs or clips. Accordingly, there is a need for a gasket to be used in hatch covers that eliminates the problems associated with using adhesives, with deterioration of the sealant qualities, and with cleaning the gasket.